Method in rock blasting operations for marking out drill hole patterns



March 4, 1969 so GUNNAR NORDGREN 3,431,049

METHOD IN ROCK BLASTING OPERATIONS FOR MARKING OUT DRILL HOLE PATTERNSFiled Sept. 7, 1966 ATTOR E United States Patent 3,431,049 METHOD INROCK BLASTING OPERATIONS FOR MARKING OUT DRILL HOLE PATTERNS Bo GunnarNordgren, 4 Mabarsstigen, Lahall, Sweden Filed Sept. 7, 1966, Ser. No.577,652 Claims priority, application Sweden, Sept. 9, 1965, 11,759/ 65US. Cl. 353-121 4 Claims Int. Cl. G031) 21/12 ABSTRACT OF THE DISCLOSUREA method of making holes for explosives for use in the blasting of rockfaces in tunnels. The method includes the steps of preparing a projectorslide in which the hole positions are located on a reduced scalecorresponding to the ratio of the sizes of the rock face and the slideand are adjusted for the particular profile of the rock face, opticallyprojecting an image of the slide onto the rock face, and drilling holesfor explosives at the positions indicated by the image.

This invention relates to a method in rock blasting operations formarking out drill hole patterns and to an apparatus for carrying outsaid method.

When constructing tunnels, drifting mines, sinking shafts or driftingraises it is generally necessary that the positions of the drill holesbe marked out on the face of the rock itself. Hitherto this has beeneffected by means of measuring rules, tape measures or mechanicaldevices which are either detached or connected to the frame-work of adrill unit or the like.

The use of such auxiliary equipment has very often meant that timeconsumed in marking out the holes has been highly disproportionate andhas sometimes caused delay in the working cycle planned for the blastingoperations. Deficiencies in acuracy of the known methods have alsocaused uneven outlining of the contours of a tunnel for instanceor havecaused the outlines to be completely wrongeither resulting in more rockbeing taken out and carried away than would have been the case if thetunnel had been marked out as intended, or too little rock being removedso that the outlines of the tunnel were too narrow to permit the passageof machines or other pieces of equipment, intended for use in saidtunnel. Besides demanding high costs and much time, subsequent blastingof the erroniously marked out profiles has resulted in tunnel walls ordrifts of less strength and reliability, owning to the unevenness of therock surface.

One main object of the invention is to avoid the aforementioneddrawbacks by applying a completely new method of marking out drill holepatterns for blasting charges, and to thereby improve the conditions foran even and strong rock surface.

Another object of the invention is to provide a method for marking outthe drill hole pattern whereby the amount of so-called surplus rock(that is the rock that lies outside the profile of the intended tunnelor drift) taken out is greatly reduced.

According to one main feature of the invention a diagram or lay-out ofthe positions of the drill hole pattern is marked out in a lighttransmitting manner on a slide of a material otherwise opaque to lightsuch as an exposed photographic film or glass sheet or cut out of ametal slide and projected against the face of the rock in which thecharges are to be placed. In this connection the diagram on the glass,metal or film slide is drawn or cut out in a reduced scale correspondingto the ratio of the size of the rock face over which the drill holepattern is desired to extend and the size of the slide and the surfaceto be projected; a scale and one or more positioning points also beingmarked on the slide, whereas conversely, an enlarged scale and one ormore corresponding measured positioning points are marked out on theface of the rock, projection of the diagram on to said face beingeffected by means of a projector positioned at a distance from the rockface, adjusted relative to the scale and set so that the positioningpoint or points projected from the slide coincide with the positioningpoint or points marked out on the face of the rock, and the projectingscale coinciding with the scale marked out on said rock face. The drillhole positions projected from the slide onto the face of the rock in theform of points of light are then suitably permanently marked out bypainting said positions onto the surface of the rock, or the light spotsrepresenting the positions can be used directly as guides for drillingthe holes intended for the blasting charge.

The projection of a plan or diagram onto a work piece from a small filmslide or the like whilst enlarging the dimensions of the work piece inaccordance with optical laws is already known, e.g. in shipbuilding. Inthis connection, however, the plans are projected onto a flat or atleast an even surface. The end wall met with in tunneling or driftingoperations, as well as when sinking shafts, etc., often presents,however, a very uneven and dark and dirty surface, where variations indepth reach from between 1 and 1.5 meters. Furthermore, in such driftingoperations the roof of the tunnel in front of the end wall is generallylower than it it is further away. It is therefore very surprising thatby means of the method according to the invention the positions of thedrill holes can be fixed on the rock face or the end wall much moreaccurately than is the case when applying previous diagrams for drillhole patterns. Corrections governed by the special contours of the endwall of the drift, particularly where there is a difference between theintended roof of the tunnel and the height of the roof of the tunnel atthe end wall of the drift, can be made without difliculty, when markingout the diagram.

Further objects and advantages of the invention will become apparentfrom the following description, considered in connection with theaccompanying drawings which form part of this specification and ofwhich:

FIG. 1 shows diagrammatically an application of the method of theinvention in a horizontal drift or tunnel.

FIG. 2 shows the end wall in the tunnel of FIG. 1 on which certainmeasurements have been made for the purpose of carrying out the method.

FIG. 3 shows diagrammatically an application of the method in a raiseand FIG. 4 shows an application of the method when sinking a shaft.

FIG 5 shows finally a modification of the method ac cording to FIGS. 1-2with a projector, used in carrying out the method, mounted on a drillunit.

Referring now particularly to FIG. 1, a tunnel is indicated generallywith the reference numeral 10, an end wall of said tunnel with referencenumeral 12, a roof thereof with 14 and a floor with 16. Standing on thefloor 16 is a projector 20 mounted on a frame 18. The projector includesin a manner known per se a light source, a slide holder, a lens,preferably having an adjustable focal length, and connected topreferably a cube-shaped casing 22 of resilient, protective material,such as rubber, plastic or similar dust and moisture tight pliable sheetmaterial. A plurality of the sides of the casing 22, preferably allexcept that from which the image is projected, are provided withattachment devices 24-. In this way the apparatus may be adjusted toproject in any desired direction in horizontal or vertical planes, bothupwards and downwards. In addition to the frame 18 it is alsoconceivable to secure the projector in suspension points, as indicateddiagrammatically in FIGS. 3 and 4, at 26 or on a firm support on thefloor 16 of the tunnel or also on a drill unit 28 as shown in FIG. 5.The means necessary for operating the projector are suitably mountedoutside the casing 22 and include at least one operating means foradjusting the sharpness of the image and if the lens has an adjustablefocal length, a sensitive, operating means for this purpose should alsobe included. The projector is also suitably provided with means foradjusting the elevation of the projector in the plane in which theprojector has been set when the apparatus was secured. These means,which are known per se, and thus need no further description in thepresent application, are also suitably operated by knobs or the likelocated outside the casing 22. The casing 22 may also be provided withconnecting means 23a for a supply of compressed air, as a driving meansfor an air operated motor 23b driving an electrical generator 230 topower the light source. In oversea countries for instance compressed airmay be the only source of energy at disposal.

The diagram of the drill hole pattern is now projected by means of thejust described projector onto the end wall 12. As can be seen from FIGS.1 and 2 the projector 20 is positioned at a distance from the end wall12 of the drift, adjusted with respect to the said scale and possiblyalso the type of lens used. The light source of the apparatus isconnected to a current source, while remaining illumination in thetunnel is subdued. The image emitted from the projector becomes visibleon the end wall 12, in the form of dots of light 30. Positioned on theslide is a positioning point which corresponds to a positioning point 32measured beforehand on the end wall. Further, the end wall has beenprovided with a scale, in the present case a horizontal one, or widthgauge 34 corresponded by a scale, reduced in the correct ratio, on theslide. The positioning point 32 and the scale 34 are preferablymanufactured from scotchlight or self-illuminating tape or in reflectingpaint. The projected image is adapted to the scale or width gauge markedout on the end wall and is focused by adjusting either the distance orthe focal length of the lens of the projector, which thus shouldpreferably be a zoom lens. The image is positioned in the correct planeby causing the positioning points on the image to coincide with thepositioning points 32 on the end Wall 12. The visible spots of light onthe end wall 12 now give exactly the positions of the drill holes in therequired blasting pattern, as marked out on the diagram on the slide.The positions of these bore holes in the blasting pattern can then bepainted on the end Wall as indications for drilling the holes in thesaid pattern. However, it is also possible, as shown in FIG. 5, to drillthe holes direct in the positions disclosed by the light spots. In FIG.the moveable drill unit 28 supports a plurality of drills which areindicated by reference numerals 36 and 38, respectively. A beam of light40 emitted from the projector creates an illuminated point 42 on the endwall and the drill 36 is indicated at this point.

Adaption of the method according to the invention in a raise 44 is shownin FIG. 3 which also shows how far the projector 20 can be moved fromthe vertical center plane of the raise without jeopardizing the accuracyof the operation. In the present case, as also in the embodimentaccording to FIG. 4, which is concerned with the sinking of a shaft 46,the projector 20 is mounted at the, diagrammatically indicated, position26.

While several more or less specific embodiments of the invention havebeen shown and described it is to be understood that this is for purposeof illustration only and that the invention is not to be limited therebybut its scope is to be determined by the appended claims.

What I claim is: 1. In the method of blasting passages through rockfaces Which extend in any desired direction which includes the steps ofmarking drill hole patterns on an uneven rock face, drilling holes atthe points indicated by said patterns, placing an explosive materialwithin the said holes, and exploding the said material to remove therock, the improvement which comprises the steps of marking the positionsof holes to be drilled onto a slide at points whose position is adjustedfor the particular profile of the rock face to be blasted and on areduced scale which corresponds to the ratio between the size of therock face over which the drill hole pattern is intended to extend andthe size of the slide,

projecting the image from the slide onto the face of the rock, and

drilling the holes for explosive at the positions indicated by theimage.

2. The method of claim 1 including placing on the slide images of atleast three non-linear positioning points,

marking on the rock face corresponding positioning points,

projecting an image of the slide on the rock face, and

adjusting the projector so that the projected images of the positioningpoints on the slide are superimposed on the corresponding points markedon the rock face.

3. The method of claim 1 including the step of painting the rock face atthe points indicated by the images of p the drill holes prior to thedrilling operation.

4. The method of claim 1 including the step of adjusting the pattern ofdrilling hole images on the slide to correspond with the irregularitiesof the rock face so that the hole images projected on the rock face willbe located at points adjusted for a non-planar rock face profile.

References Cited NORTON ANSI-IER, Primary Examiner.

R. M. SHEER, Assistant Examiner.

US. Cl. X.R. 353-11

